In the wake of increasing atmospheric damage as a result of the release of refrigerants to the atmosphere, a growing demand for high efficiency refrigerant reclamation systems has emerged. As a clearer understanding of the nature of the environmental damage caused by refrigerants is developed, the pressure to control the damage continues to rise. In the past, routine practice within the refrigeration industry saw the release of many refrigerants to the environment either accidentally due to appliance failure or on purpose during maintenance. As is well known, research has revealed that such practice contributes to the deterioration of the ozone layer and as a result, apparatuses and methods for the reclamation of refrigerants have been developed.
At the present time, there are a large variety of refrigerants in use, each of which have their own properties adapted or effective within particular refrigeration apparatuses. As a result, there is an increasing demand for highly effective refrigerant reclamation systems having the capabilities of reclaiming the large number of refrigerants found in the industry. With the majority of reclamation systems displaying refrigerant type-specific capacity, the versatility of such a practice has been limited to date.
Typically, recovered refrigerants are contaminated with oil, moisture, acids, non-condensibles and particulates and, as such, it is desirable to employ a reclamation system which can effectively remove these contaminants from a variety of refrigerants. Specifically, there has been a need for a system which provides stringent reclamation capacity for both high and low pressure refrigerants.
To date, the majority of reclamation systems employ a compressor unit in fluid communication with a source refrigerant wherein the compressor facilitates the removal of a refrigerant from its source container. The crankcase of a compressor contains a volume of oil for the lubrication of the moving parts of the compressor and this oil source is routinely open for mixing with the incoming refrigerant. When the source refrigerant directly encounters a compressor unit, some degree of oil contamination is likely where oil contaminates the refrigerant and refrigerant contaminates the oil. As a result of this cross-contamination, regular maintenance of the compressor is required, specifically requiring the oil of the compressor be changed with each new refrigerant being run through the system so as to prevent the mixing of various refrigerants and their contaminants and, secondly, to limit the direct effects of the contaminants on the compressor.
In addition to the precautions necessary to avoid cross-contamination, the physical properties of refrigerants differ to the extent that no single compressor will be compatible with all refrigerants with the efficiency and energy consumption of compressors varying with the type of refrigerant being processed. For example, systems designed for certain refrigerants may preferably operate with open-type compressors. However, open-type compressors are more prone to leaks and require more maintenance than hermetic type compressors.
The efficiency of compressors is also dependent on the velocity and carrying capacity of the system. In an example where a system displaying small interconnecting piping and a small distillation chamber is coupled with a high capacity compressor, contaminants such as moisture will frequently carry over from the distillation chamber.
Still further, other inefficiencies in refrigeration reclamation practice include the removal of oil and non-condensibles. Efforts to remove oil contamination from refrigerants routinely employ oil separators in series with the compressor. As indicated above, a compressor will add oil to the refrigerant which must subsequently be removed by the oil separator, a process which is inherently inefficient. Although a high percentage of the oil is typically removed by an oil separator, some oil is likely to remain in the refrigerant when processed in this manner. Similarly, great difficulty is experienced in the removal of non-condensibles carried through the compressor.
A review of the prior art has revealed a number of references relating to refrigerant recovery. For example, Laukhuf et al. teach of a refrigeration recovery and purification system in U.S. Pat. No. 5,193,351 wherein a refrigerant compressor is connected with a refrigeration unit under service and a refrigerant recovery system. A recovered refrigerant is fed directly to an oil separator for the removal of oil contamination and onward through a pressure regulator to a refrigerant compressor. Upon retrieval via the compressor, the reclaimed refrigerant is at least partially liquefied as it continues along through the condenser, en route to a storage container. In conjunction with the retrieval pathway, a closed pathway from the storage container through a filter apparatus and back to the condenser, operates under the control of a liquid pump, thus purifying and cooling the passing liquid.
In this manner, reclaimed refrigerants directly contact and potentially contaminate the receiving compressor with particulate, acid and moisture. Consequently, frequent maintenance of the compressor unit is likely, and reclamation of a variety of refrigerants limited.
Alternatively, in U.S. Pat. No. 5,245,840 Van Steenburgh Jr., teaches of a refrigerant reclaim method and apparatus comprising two refrigeration pathways wherein a primary pathway includes a compressor and drives the refrigerant through a secondary pathway including an oil separator and a receiving cylinder. The two pathways therein described interact by ways of a first and second heat exchange element. An incoming refrigerant enters the cold side of a first heat exchange element which provides vaporization of the refrigerant. The refrigerant vapor then passes through an oil separator to filter off oil and water. Upon exiting the oil separator, the refrigerant vapor passes through the hot side of the second heat exchange element, thereby becoming liquefied. The liquified refrigerant is subsequently introduced into a storage cylinder. In another embodiment of this reference, the reclaimed refrigerant is recirculated back through the oil separator unit by introducing the refrigerant into the cold side of the first heat exchange element. An alternative method to further purify the reclaimed refrigerant teaches of a method of further cycling the refrigerant from the storage cylinder through a drier unit (liquid).